Electrostatic separating apparatus



Oct. 14, 1941. H, B, JQHNSQN 2,258,767

ELECTROSTATIC SEPARATING APPARATUS Filed Sept. l, 1939 ATTORNEYS. ai

Patented ocr. 14, 1941 UNITED STATE ELECTROSTATIVC SEPARATING APPARATUSt Herbert B. Johnson, Rochester, N. Y., assignor to Ritter ProductsCorporation, Rochester, N. Y., a corporation of New York ApplicationSeptember 1, 1939, Serial No.1292,980

3 Claims. (Cl. 209-127) My invention relates, generally, toelectrostatic separating apparatus and it has particular relation toimprovements in the electrode construction thereof.

In my Patent No. 2,135,716, issued November 8, 1938, I have shown aplurality of pairs of 'separating electrodes which are connected acrossa source of high direct'voltage as a result of which a high potentialelectrostatic field is maintained between each of the pairs ofelectrodes. The electrodes are generally cylindrical in shape and bothof them are rotatable. The material to be separated falls onto one ofthem, called the material conveying electrode, and it is carried therebyinto the electrostatic field where the separating action takes place. Itis highly desirable that the high potential electrode have a smoothsurface at all times in order to prevent the piling up of particlesthereon thereby forming discharge points and causing arcing to takeplace between the electrodes. `In my patent I have provided a wiper thatis stationarily mounted with respect to the high potential electrode andengages its surface as it rotates for the purpose of polishing it andremoving therefrom any particles which might tend to form dischargepoints. While this construction is generally satisfactory, I have foundthat it is, likely to result in the wearing of A grooves in the highpotential electrode due to the lodging of relatively hard particles inthe wiper in such manner as to serve as cutting edges. This isundesirable since it results in a roughened surface on the highpotential electrode and the formation of sharp corners or points fromwhich arcing may take place.

Accordingly, it is to the solution of this problem that my presentinvention is addressed.

|lhe object of my invention, generally stated, is to provide for causingrelative longitudinal movement between a rotatable cylindrical electrodeof a pair of separating electrodes and a wiper associated therewith.

Another object of my invention is to provide for causing longitudinalmovement of the wiper relative to the associated electrode.

Still another object of my invention is to cause longitudinal movementof an electrode relative to a wiper stationarily mounted with respectthereto.

Still another object of my invention is to provide'for translating therelative movement of an electrode into relative longitudinal movement ofa wiper associated therewith.

A further object of my invention is to provide for repeatedly jarringone of the electrodes in order to'cause particles thereon to fall o. l

Otherobjects of my invention will, in part, be obvious and in partappear hereinafter.

more readily My invention, accordingly, is disclosed in the nembodiments thereof shown in the accompanying drawings, and it comprisesthe features of construction, combinationof elements and arrangement ofparts which will be exemplified in the constructions hereinafter setforth, and the scope of the application of which will be indicated inthe appended claims.

For a more complete understanding of the nature andv scope of my.invention, reference may be had to the following detailed descriptiontaken in connection lwith the accompanying drawing, in which:

Figure 1 is a view, in front elevation, of a high potential electrodeand wiper therefor arranged to be osclllated with respect thereto;

Figure 2 is a detail sectional view, taken along the line 2-2 of Figure1, showing, in addition, the material conveying electrode;

Figure 3 shows a modification of the construction illustrated in Figure1; and

Figure 4 shows still another modification of the constructionillustrated in Figure 1.

Referring now particularly to Figures 1 and 2 .t of the drawing, it willbe observed that the refelectrode that is generally cylindrical in shapejonto which the particles of material to arated fall and by means ofwhich they are conerence character Ill designates a high potential andmay be of any desired length. The electrode I0 forms one of a pair ofelectrodes, the other electrode II being a material conveying electrodebe Sepveyed into the electrostatic field that is maintainedabetweenelectrodes I0 and II under normal operating conditions by connection toa suitable source of high voltage direct current. An angle I2 isprovided for guiding the material to be separated onto the materialconveying electrode Il. between the electrode II and the angle I2becomes filled with the material to be separated It will be understoodthat the space j l1 that are carried by uprights IB and I9,respectively. Any suitable means may be provided for rotating the highpotential electrode III. For example, a gear wheel 20 may be provided onthe shaft I5, as shown, and it may be driven through suitable drivingmeans as will be readily understood.

The material conveying electrode II is arranged to be rotated in thedirection indicated by the arrow 2|. The high potential electrode I maybe rotated in either direction depending upon the operating conditions.

As set forth in my patent, referred to hereinbefore, it is desirable tomaintain the surface of the high potential electrode III in a polishedcondition in order to prevent the building up of discharge pointsthereon as a result of the collection of particles on the surface of thematerial being separated. For this purpose a wiper 24 is provided whichextends substantially the entire length of the high potential electrodeI3 and covers about one quarter of its circumference. The wiper 24 maybe formed of felt impregnated with a suitable abrasive material such asfinely ground Carborundum, rouge, crocus,

, aluminum oxide or otherpolishing powder. The

wiper 24 is held in proper position by means of a support member 25 inthe form of a metal strip to which the wiper may be cemented.

' Ears 25 are provided at the ends of the support member 25 and they areattached, as shown, to the ends of insulators 21 which are similar tothe insulators I3. The insulators 21 are mounted on short shafts 28 and29 which are arranged'for endwise movement in bearings 30 and 3 I,respectively, that are suitably mounted on the uprights I8 and I9.

As previously indicated, it is desirable to provide for relativelongitudinal movement between the high potential electrode I0 and thewiper 24 in order to prevent pitting of the surface of the electrode.For this purpose collars 34 and 35 are provided at the ends of theinsulators I3 with sinuous grooves 35 and 31 therein, as illustrated.Cooperating with these grooves 35 and 31 are pins 38 and 39 which extendfrom end members 40 and 4I, respectively, of the insulators 21. Ifdesired, the pins 38 and 33 may be provided with antifriction rollers inorder to reduce the friction with the sides of the grooves 36 and 31.

It will now be apparent that rotation of the electrode l0 relative tothe wiper 24 causes, in addition, relative longitudinal movement betweenit and the wiper 24 because of the endwise movement thereof in thebearings 30 and 3I as the pins 38 and 39 follow the grooves 35 and 31.In this wise the surface of the electrode I0 is 'maintained smooth andpolished and there is no likelihood of the formation of grooves thereinas a result of the presence of hard particles in the wiper 24.

The material conveying electrode I I may also be provided with a wiper42 which is formed of material that is similar to the material of whichthe. wiper 24 is formed and impregnated as described. The wiper 42 maybe held in place by any suitable means on the angle AI2 such as by bolts43, as shown.

In Figure 3 of the drawing there is shown another embodiment of myinvention. As in the construction as shown in Figure 1 of the drawing,the high potential electrode I0 is arranged for rotary motion only whilethe wiper 24 and its support member 25 are mounted for endwise movementin the bearings 30 and 3|. The support member 25 and associated partsare biased to the right as viewed in the drawing by a compression spring45 which reacts against a suitable reaction member 45 that may becarried by the upright I5. In order to move the support 25 and the wiper24 carried thereby longitudinally of the electrode I0, a cam 41 ismounted on a shaft 4l and isarranged to y'engage the right hand end ofthe short shaft 23, as shown. The cam 41 may be yrotated by any suitablemeans such as through a gear 43 mounted on. the shaft 43 and driven fromany suitable driving means.

It willgbe apparent that the rotation of the cam 41 will cause Iendwisemovement of the support 25 and the wiper 24 carried thereby relative tothe electrode I0 in one direction and that movement in the oppositedirection will be effected by the spring 45. This relative longi tudinalmovement will take place while the electrode IU is being rotated asdescribed. The desired polishing action of the surface of the electrodewill then be effected because of the combined rotary and translatorymovement of it with respect to the wiper 24.

In Figure 4 of the drawing there is shown another embodiment of myinvention. In this embodiment the electrode I0 is mounted for endwisemovement relative to bearings I5' and I1', while the wiper 24 and thesupport 25 therefore are arranged to be relatively stationary. Insteadof moving thewiper 24 along the surface of the lzelectrode, theelectrode is moved along the wiper As shown. the electrode I0 is biasedto the right, as viewed in the drawing, by a compression spring 5I thatis mounted within a suitable tubular housing 52 carried by the uprightI5. An ad- Vjustable plug 53 is threaded into the end of the tubularhousing, 5I and its position can be changed in order to vary the biasingforce of the spring 5I.

In order to effect endwise movement of the electrode I0 in the oppositedirection, the ratchet wheel 54 is mounted on the shaft I5 and it isarranged to engage a tooth or pawl 55 that may be carried by anysuitable support, such as the support member that is mounted on theupright I3. As the electrode I0 is rotated through the gear 2li, it willbev moved endwise to the left as the teeth of the ratchet wheel 54 rideover the tooth or pawl 55. 'The spring 5I will return the electrode I0to the right as each tooth of the ratchet wheel 54 is passed.

Because the electrode Ill is moved to the right sharply by the spring 5Ias soon as each tooth of the ratchet wheel 54 is passed, a certainamount of jarring action takes place which tends to shake oif particlesthat might otherwise tend to cling to the surface of the electrode III.This action, in addition to the relative rotary and translatory movementbetween the wiper 24 and the electrode I 0 serves to keep the surface ofthe electrode free from any of the particles of the material beingseparated and at the same time prevents the formation of ridges orgrooves in the electrode surface.

Obviously the positions of the ratchet wheel 54 and of the tooth or pawl55 could be reversed without departing from the scope of this invention,SinceV further changes may also be made in the above constructions anddifferent embodiments of the invention may be made without departingfrom its scope,-it is intended that all matters contained in theforegoing description or shown in the accompanying drawing shall benterpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In an electrostatic separator for separating a product comprisingmixed particles, in combination, a rotatable cylindrical electrode,wiper means containing abrasive material cooperating with said electrodefor polishing the same and extending substantially the entire lengththereof, and pin and cam means operatively interconnecting saidelectrode and said Wiper means whereby rotation of the former causesslight relative longitudinal movement between said electrode and wipermeans 2. In an electrostatic separator for separating a productcomprising mixed particles, in ccmbination, a rotatable cylindricalelectrode, wiper means containing abrasive material cooperating withsaid electrode for polishing the same and extending substantially theentire length thereof,

insulator means mounting said electrode and wiperY means for relativelongitudinal movement, and pin and cam means operatively interconnecting said vinsulator means remote from said electrode and wiper meanswhereby rotation of the former causes slight relative longitudinalmovement between said electrode and wiper means.

3. In an electrostatic separator for separating a, product comprisingmixed particles, in combination, a rotatable cylindrical electrodehaving rotatable therewith a. sinuous groove, wiper means containingabrasive material extending substantially the entire length of saidelectrode and engaging the same and movable longitudinally thereof forpolishing the same, and a pin carried by said wiper means and extendinginto said sinuous groove whereby the Vrotary movement of said electrodeis translated into longitudinal movement of said wiper means.

HERBERT B. JOHNSON.

